Sales_by_Match.java

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

class Result {

    /*
     * Complete the 'sockMerchant' function below.
     *
     * The function is expected to return an INTEGER.
     * The function accepts following parameters:
     *  1. INTEGER n
     *  2. INTEGER_ARRAY ar
     */

    public static int sockMerchant(int n, List<Integer> ar) {
    // Write your code here
        
        int pair = 0;
        List<Integer> matchedIndxes = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            if (matchedIndxes.contains(i)) {
                continue;
            }
            for (int j = 0; j < n; j++) {
                if (j == i || matchedIndxes.contains(j)) {
                    continue;
                }
                if (ar.get(i) == ar.get(j)) {
                    pair++;
                    matchedIndxes.add(i);
                    matchedIndxes.add(j);
                    break;
                }
            }
        }        
        return pair;
    }
}

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        int n = Integer.parseInt(bufferedReader.readLine().trim());

        String[] arTemp = bufferedReader.readLine().replaceAll("\\s+$", "").split(" ");

        List<Integer> ar = new ArrayList<>();

        for (int i = 0; i < n; i++) {
            int arItem = Integer.parseInt(arTemp[i]);
            ar.add(arItem);
        }

        int result = Result.sockMerchant(n, ar);

        bufferedWriter.write(String.valueOf(result));
        bufferedWriter.newLine();

        bufferedReader.close();
        bufferedWriter.close();
    }
}